SD Card transfer rate

FAQ, getting help, user experience about PrimoCache
Post Reply
Sheldon
Level 1
Level 1
Posts: 1
Joined: Mon Aug 30, 2021 7:27 pm

SD Card transfer rate

Post by Sheldon »

I have just purchased this software. I left everything at the default settings and am using a 40GBs partition on an NVME drive for my cache. I haven't tested transfer speeds from one drive to another yet. but in transferring from my SD card to an external drive I am getting the usual transfer speed. Will this work with a card reader and if it will do I need to adjust my settings? Thanks. Sheldon.
User avatar
Jaga
Contributor
Contributor
Posts: 692
Joined: Sat Jan 25, 2014 1:11 am

Re: SD Card transfer rate

Post by Jaga »

Welcome to the forums Sheldon.

It should work well with an external drive, provided that drive uses a standard volume type recognizable by Windows. i.e. FAT32, NTFS, etc. If it has a proprietary software suite & driver that changes things a little, but if you're copying from your local NVMe to the external, then the cache will function fine as intended with the NVMe.

However having said that - for the cache to really function well, the data has to not only be read once, but re-read multiple times over that. The premise a cache works on is repeat access to the same data which makes it into the cache and is then accessed more quickly. If you simply copy something one time from the NVMe to the external drive you'll get normal read speeds. The second, third, etc times it will (if the data becomes cached) read much more quickly.

What I think you're experiencing is bottlenecking in write speeds with the external drive. Or the USB speed may be holding it back. Normally the NVMe speeds would easily exceed an external USB drive with or without a cache. So the cache in this case probably isn't holding you back. The way to resolve it would be to remove the NVMe from the cache task, and add the external drive along with a short (10s or less) deferred write time to the task. That will let the NVMe run at it's full native speed, while the external benefits from a write cache. You'll have to be careful about removing the external drive (flushing the write cache fully before dismounting the drive) of course.
InquiringMind
Level SS
Level SS
Posts: 477
Joined: Wed Oct 06, 2010 11:10 pm

Re: SD Card transfer rate

Post by InquiringMind »

I'd agree with Jaga - PrimoCache should work with volumes in card readers (assuming you've set up a cache task for them) but simple file copying doesn't benefit much from caching - and without further details on the external drive (HDD? SSD? USB1/2/3? eSATA?) it's tricky to pinpoint the bottleneck. Most SD cards have pretty poor read/write speeds though, compared to SSDs.

A disk benchmark like CrystalDiskMark should show a significant difference - but the majority of its workload is repeated reads and writes which PrimoCache will boost significantly.
Post Reply